Results for "Kartik Srinivasan"

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Efficient spectroscopy of single embedded emitters using optical fiber taper waveguidesApr 17 2009Jun 11 2009A technique based on using optical fiber taper waveguides for probing single emitters embedded in thin dielectric membranes is assessed through numerical simulations. For an appropriate membrane geometry, photoluminescence collection efficiencies in excess ... More
Sub-nanosecond Electro-optic Modulation of Triggered Single Photons from a Quantum DotMar 18 2011Control of single photon wave-packets is an important resource for developing hybrid quantum systems which are composed of different physical systems interacting via photons. Here we extend this control to triggered photons emitted by a quantum dot, temporally ... More
Nonlinear Oscillations and Bifurcations in Silicon Photonic MicroresonatorsOct 15 2013Feb 26 2014Silicon microdisks are optical resonators that can exhibit surprising nonlinear behavior. We present a new analysis of the dynamics of these resonators, elucidating the mathematical origin of spontaneous oscillations and deriving predictions for observed ... More
Coherent coupling between radio frequency, optical, and acoustic waves in piezo-optomechanical circuitsAug 06 2015The interaction of optical and mechanical modes in nanoscale optomechanical systems has been widely studied for applications ranging from sensing to quantum information science. Here, we develop a platform for cavity optomechanical circuits in which localized ... More
Si$_3$N$_4$ optomechanical crystals in the resolved-sideband regimeNov 25 2013Nov 26 2013We demonstrate sideband-resolved Si$_3$N$_4$ optomechanical crystals supporting $10^5$ quality factor optical modes at 980 nm, coupled to $\approx4$ GHz frequency mechanical modes with quality factors of $\approx3000$. Optomechanical electromagnetically ... More
Electromagnetically induced transparency and wide-band wavelength conversion in silicon nitride microdisk optomechanical resonatorsFeb 12 2013Jun 03 2013We demonstrate optomechanically-mediated electromagnetically-induced transparency and wavelength conversion in silicon nitride (Si3N4) microdisk resonators. Fabricated devices support whispering gallery optical modes with a quality factor (Q) of 10^6, ... More
Wide Stiffness Range Cavity Optomechanical Sensors for Atomic Force MicroscopyMay 14 2012We report on progress in developing compact sensors for atomic force microscopy (AFM), in which the mechanical transducer is integrated with near-field optical readout on a single chip. The motion of a nanoscale, doubly-clamped cantilever was transduced ... More
Background-free quantum frequency conversion of single photons from a semiconductor quantum dotMay 10 2012We demonstrate background-free quantum frequency conversion of single photons from an epitaxially-grown InAs quantum dot. Single photons at \approx 980 nm are combined with a pump laser near 1550 nm inside a periodically-poled lithium niobate (PPLN) waveguide, ... More
Probing the dispersive and spatial properties of planar photonic crystal waveguide modes via highly efficient coupling from optical fiber tapersAug 12 2003The demonstration of an optical fiber based probe for efficiently exciting the waveguide modes of high-index contrast planar photonic crystal (PC) slabs is presented. Utilizing the dispersion of the PC, fiber taper waveguides formed from standard silica ... More
Fiber-coupled semiconductor waveguides as an efficient optical interface to a single quantum dipoleMay 18 2009Sep 17 2009We theoretically investigate the interaction of a single quantum dipole with the modes of a fiber-coupled semiconductor waveguide. Through a combination of tight modal confinement and phase-matched evanescent coupling, we predict that approximately 70 ... More
Linear and nonlinear optical spectroscopy of a strongly-coupled microdisk-quantum dot systemJul 23 2007Jul 27 2007A fiber taper waveguide is used to perform direct optical spectroscopy of a microdisk-quantum-dot system, exciting the system through the photonic (light) channel rather than the excitonic (matter) channel. Strong coupling, the regime of coherent quantum ... More
Optical fiber taper coupling and high-resolution wavelength tuning of microdisk resonators at cryogenic temperaturesNov 14 2006A system for studying microcavity resonators at cryogenic temperatures (~10 K) through evanescent coupling via optical fiber taper waveguides is reported, and efficient fiber coupling to AlGaAs microdisk cavities with embedded quantum dots is demonstrated. ... More
Mode Coupling and Cavity-Quantum-Dot Interactions in a Fiber-Coupled Microdisk CavityJun 17 2006Jan 26 2007A quantum master equation model for the interaction between a two-level system and whispering-gallery modes (WGMs) of a microdisk cavity is presented, with specific attention paid to current experiments involving a semiconductor quantum dot (QD) embedded ... More
Design of two-dimensional photonic crystal defect states for quantum cascade laser resonatorsOct 11 2004Current quantum cascade lasers based upon conduction band electron transitions are predominantly TM (electrical field normal to the epitaxial direction) polarized. Here we present a study of localized defect modes, with the requisite TM polarization, ... More
Wide-span and tunable-wavelength photon pairs around 1.55 μm from a silicon nanophotonic chipApr 17 2013Using a compact optically-pumped silicon nanophotonic chip consisting of coupled silicon microrings, we generate photon pairs in multiple pairs of wavelengths around 1.55 \mu m. The wavelengths are tunable over several nanometers, demonstrating the capability ... More
Optomechanical transduction of an integrated silicon cantilever probe using a microdisk resonatorSep 28 2010Sensitive transduction of the motion of a microscale cantilever is central to many applications in mass, force, magnetic resonance, and displacement sensing. Reducing cantilever size to nanoscale dimensions can improve the bandwidth and sensitivity of ... More
Integrated silicon optomechanical transducers and their application in atomic force microscopyMay 14 2014This chapter describes the basic design, simulation, and fabrication for fully Si integrated, waveguide coupled, optomechanical force and displacement sensors. The approach of full Si integration of all stationary nanophotonic components with mechanically ... More
Quantum Transduction of Telecommunications-band Single Photons from a Quantum Dot by Frequency UpconversionApr 15 2010Aug 19 2011The ability to transduce non-classical states of light from one wavelength to another is a requirement for integrating disparate quantum systems that take advantage of telecommunications-band photons for optical fiber transmission of quantum information ... More
Hybrid gap modes induced by fiber taper waveguides: application in spectroscopy of single solid-state emitters deposited on thin filmsFeb 19 2010We show, via simulations, that an optical fiber taper waveguide can be an efficient tool for photoluminescence and resonant, extinction spectroscopy of single emitters, such as molecules or colloidal quantum dots, deposited on the surface of a thin dielectric ... More
Quantum Electromechanics on Silicon Nitride NanomembranesDec 15 2015Dec 16 2015We present a platform based upon silicon nitride nanomembranes for integrating superconducting microwave circuits with planar acoustic and optical devices such as phononic and photonic crystals. Utilizing tensile stress and lithographic patterning of ... More
Kerr Microresonator Soliton Frequency Combs at Cryogenic TemperaturesJun 15 2019We present measurements of silicon nitride nonlinear microresonators and frequency comb generation at cryogenic temperatures as low as 7~K. The resulting two orders of magnitude reduction in the thermo-refractive coefficient relative to room-temperature ... More
Photonic waveguide mode to free-space Gaussian beam extreme mode converterMar 06 2018Integration of photonic chips with atomic, micromechanical, chemical and biological systems can advance science and open many possibilities in chip-scale devices and technology. Compact photonic structures for direct coupling of light between high-index ... More
Fabrication-tolerant high quality factor photonic crystal microcavitiesDec 09 2003A two-dimensional photonic crystal microcavity design supporting a wavelength-scale volume resonant mode with a calculated quality factor (Q) insensitive to deviations in the cavity geometry at the level of Q~2x10^4 is presented. The robustness of the ... More
A microelectromechanically controlled cavity optomechanical sensing systemApr 04 2012Microelectromechanical systems (MEMS) have been applied to many measurement problems in physics, chemistry, biology and medicine. In parallel, cavity optomechanical systems have achieved quantum-limited displacement sensitivity and ground state cooling ... More
Nonlinear absorption and dispersion in fiber-taper-coupled silicon photonic crystal microresonatorsDec 01 2004A technique is demonstrated which efficiently transfers light between a tapered standard single-mode optical fiber and a high-Q, ultra-small mode volume, silicon photonic crystal resonant cavity. Cavity mode quality factors of 47000 are measured, and ... More
Optical fiber coupling to planar photonic crystal microcavitiesMay 13 2004A technique is demonstrated which efficiently transfers light between a tapered standard single-mode optical fiber and a resonant mode of a high-Q photonic crystal cavity with mode volume less than a cubic wavelength in size. Cavity mode quality factors ... More
Efficient and low-noise single-photon-level frequency conversion interfaces using silicon nanophotonicsOct 08 2015Optical frequency conversion has applications ranging from tunable light sources to telecommunications-band interfaces for quantum information science. Here, we demonstrate efficient, low-noise frequency conversion on a nanophotonic chip through four-wave-mixing ... More
Si$_3$N$_4$ nanobeam optomechanical crystalsNov 21 2014Dec 04 2014The development of Si$_3$N$_4$ nanobeam optomechanical crystals is reviewed. These structures consist of a 350 nm thick, 700 nm wide doubly-clamped Si$_3$N$_4$ nanobeam that is periodically patterned with an array of air holes to which a defect region ... More
The First Law of Black Hole Mechanics for Fields with Internal Gauge FreedomNov 02 2015Jun 16 2016We derive the first law of black hole mechanics for physical theories based on a local, covariant and gauge-invariant Lagrangian where the dynamical fields transform non-trivially under the action of internal gauge transformations. The theories of interest ... More
Bright single photon emission from a quantum dot in a circular Bragg grating microcavityDec 18 2011Bright single photon emission from single quantum dots in suspended circular Bragg grating microcavities is demonstrated. This geometry has been designed to achieve efficient (> 50 %) single photon extraction into a near-Gaussian shaped far-field pattern, ... More
Feasibility of detecting single atoms using photonic bandgap cavitiesFeb 13 2004We propose an atom-cavity chip that combines laser cooling and trapping of neutral atoms with magnetic microtraps and waveguides to deliver a cold atom to the mode of a fiber taper coupled photonic bandgap (PBG) cavity. The feasibility of this device ... More
pyLLE: a Fast and User Friendly Lugiato-Lefever Equation SolverMar 22 2019May 30 2019We present the development of pyLLE, a freely accessible and cross-platform Lugiato-Lefever equation solver programmed in Python and Julia and optimized for the simulation of microresonator frequency combs. Examples illustrating its operation, the simplicity ... More
pyLLE: a Fast and User Friendly Lugiato-Lefever Equation SolverMar 22 2019We present the development of pyLLE, a freely accessible and cross-platform Lugiato-Lefever equation solver programmed in Python and Julia and optimized for the simulation of microresonator frequency combs. Examples illustrating its operation, the simplicity ... More
Nanoscale optical positioning of single quantum dots for bright and pure single-photon emissionMar 24 2015Aug 05 2015Self-assembled, epitaxially-grown InAs/GaAs quantum dots are promising semiconductor quantum emitters that can be integrated on a chip for a variety of photonic quantum information science applications. However, self-assembled growth results in an essentially ... More
Low-noise on-chip frequency conversion by four-wave-mixing Bragg scattering in SiNx waveguidesMar 29 2012Jun 12 2012Low-noise, tunable wavelength-conversion through non-degenerate four-wave mixing Bragg scattering in SiNx waveguides is experimentally demonstrated. Finite element method simulations of waveguide dispersion are used with the split-step Fourier method ... More
Tuning and Stabilization of Optomechanical Crystal Cavities Through NEMS IntegrationJun 25 2018Nanobeam optomechanical crystals, in which localized GHz frequency mechanical modes are coupled to wavelength-scale optical modes, are being employed in a variety of experiments across different material platforms. Here, we demonstrate the electrostatic ... More
Rayleigh scattering, mode coupling, and optical loss in silicon microdisksJun 22 2004Jun 24 2004High refractive index contrast optical microdisk resonators fabricated from silicon-on-insulator wafers are studied using an external silica fiber taper waveguide as a wafer-scale optical probe. Measurements performed in the 1500 nm wavelength band show ... More
Fiber-based cryogenic and time-resolved spectroscopy of PbS quantum dotsDec 01 2010PbS quantum dots are promising active emitters for use with high-quality Si nanophotonic devices in the telecommunications-band. Measurements of low quantum dot densities are limited both because of low fluorescence levels and the challenges of single ... More
Efficient input and output fiber coupling to a photonic crystal waveguideNov 03 2003The efficiency of evanescent coupling between a silica optical fiber taper and a silicon photonic crystal waveguide is studied. A high reflectivity mirror on the end of the photonic crystal waveguide is used to recollect, in the backwards propagating ... More
Single quantum dot spectroscopy using a fiber taper waveguide near-field opticJun 13 2007Photoluminescence spectroscopy of single InAs quantum dots at cryogenic temperatures (~14 K) is performed using a micron-scale optical fiber taper waveguide as a near-field optic. The measured collection efficiency of quantum dot spontaneous emission ... More
Photoluminescence measurements of quantum-dot-containing semiconductor microdisk resonators using optical fiber taper waveguidesJun 11 2005Fiber taper waveguides are used to improve the efficiency of room temperature photoluminescence measurements of AlGaAs microdisk resonant cavities with embedded self-assembled InAs quantum dots. As a near-field collection optic, the fiber taper improves ... More
Phased-Locked Two-Color Single Soliton Microcombs in Dispersion-Engineered Si3N4 ResonatorsMar 25 2018We propose and theoretically investigate a dispersion-engineered Si3N4 microring resonator, based on a cross-section containing a partially-etched trench, that supports phase-locked, two-color soliton microcomb states. These soliton states consist of ... More
Slot-Mode Optomechanical Crystals: A Versatile Platform for Multimode OptomechanicsAug 24 2015We demonstrate slot-mode optomechanical crystals, a class of device in which photonic and phononic crystal nanobeam resonators separated by a narrow slot are coupled through optomechanical interactions. In these geometries, nanobeam pairs are patterned ... More
Spectral broadening and shaping of nanosecond pulses: towards shaping of single photons from quantum emittersJul 14 2014We experimentally demonstrate spectral broadening and shaping of exponentially-decaying nanosecond pulses via nonlinear mixing with a phase-modulated pump in a periodically-poled lithium niobate (PPLN) waveguide. A strong, 1550~nm pulse is imprinted with ... More
An optical fiber-based probe for photonic crystal microcavitiesJun 26 2004We review a novel method for characterizing both the spectral and spatial properties of resonant cavities within two-dimensional photonic crystals (PCs). An optical fiber taper serves as an external waveguide probe whose micron-scale field is used to ... More
A chip-scale, telecommunications-band frequency conversion interface for quantum emittersApr 21 2013Sep 06 2013We describe a chip-scale, telecommunications-band frequency conversion interface designed for low-noise operation at wavelengths desirable for common single photon emitters. Four-wave mixing Bragg scattering in silicon nitride waveguides is used to demonstrate ... More
Investigations of a coherently driven semiconductor optical cavity QED systemJun 25 2008Chip-based cavity quantum electrodynamics (QED) devices consisting of a self-assembled InAs quantum dot (QD) coupled to a high quality factor GaAs microdisk cavity are coherently probed through their optical channel using a fiber taper waveguide. We highlight ... More
Optical-fiber based measurement of an ultra-small volume high-Q photonic crystal microcavitySep 25 2003A two-dimensional photonic crystal semiconductor microcavity with a quality factor Q ~ 40,000 and a modal volume Veff ~ 0.9 cubic wavelengths is demonstrated. A micron-scale optical fiber taper is used as a means to probe both the spectral and spatial ... More
Cavity Q, mode volume, and lasing threshold in small diameter AlGaAs microdisks with embedded quantum dotsNov 17 2005The quality factor (Q), mode volume (Veff), and room-temperature lasing threshold of microdisk cavities with embedded quantum dots (QDs) are investigated. Finite element method simulations of standing wave modes within the microdisk reveal that Veff can ... More
Microwave-to-optical transduction using coupled piezoelectric and optomechanical resonatorsJul 10 2019The successes of superconducting quantum circuits at local manipulation of quantum information and photonics technology at long-distance transmission of the same have spurred interest in the development of quantum transducers for efficient, low-noise, ... More
The Lusternik-Schnirelmann category of metric spacesFeb 08 2014Apr 18 2014We extend the theory of the Lusternik-Schnirelmann category to general metric spaces by means of covers by arbitrary subsets. We also generalize the definition of the strict category weight. We show that if the Bockstein homomorphism on a metric space ... More
Strongly Exponential Separation Between Monotone VP and Monotone VNPMar 05 2019We show that there is a sequence of explicit multilinear polynomials $P_n(x_1,\ldots,x_n)\in \mathbb{R}[x_1,\ldots,x_n]$ with non-negative coefficients that lies in monotone VNP such that any monotone algebraic circuit for $P_n$ must have size $\exp(\Omega(n)).$ ... More
Motivic Decomposition of Projective Pseudo-homogeneous VarietiesSep 21 2015Oct 19 2017Let $G$ be a semi-simple algebraic group over a perfect field $k$. A lot of progress has been made recently in computing the Chow motives of projective $G$-homogenous varieties. When $k$ has positive characteristic, a broader class of $G$-homogeneous ... More
Codes on Varieties as Codes on CurvesMar 14 2013The discovery of algebraic geometric codes constructed on curves led to generalizing this construction on higher dimensional varieties. In this paper, we use a theorem of B. Poonen to show that the codes obtained from higher dimensional varieties can ... More
Conductors and minimal discriminants of hyperelliptic curves with rational Weierstrass pointsAug 21 2015Let $C$ be a hyperelliptic curve of genus $g$ over the fraction field $K$ of a discrete valuation ring $R$. Assume that the residue field $k$ of $R$ is perfect and that $\mathop{\textrm{char}} k \neq 2$. Assume that the Weierstrass points of $C$ are $K$-rational. ... More
An invariant in shock clustering and Burgers turbulenceJun 15 2011Jan 06 20121-D scalar conservation laws with convex flux and Markov initial data are now known to yield a completely integrable Hamiltonian system. In this article, we rederive the analogue of Loitsiansky's invariant in hydrodynamic turbulence from the perspective ... More
Rates of convergence for Smoluchowski's coagulation equationsMay 21 2009Apr 24 2011We establish nearly optimal rates of convergence to self-similar solutions of Smoluchowski's coagulation equation with kernels $K = 2$, $x + y$, and $xy$. The method is a simple analogue of the Berry-Ess\'een theorem in classical probability and requires ... More
An Extension of the Lovasz Local Lemma, and its Applications to Integer ProgrammingJul 18 2003The Lovasz Local Lemma due to Erdos and Lovasz is a powerful tool in proving the existence of rare events. We present an extension of this lemma, which works well when the event to be shown to exist is a conjunction of individual events, each of which ... More
On the Lusternik-Schnirelmann category of Peano continuaDec 04 2012Aug 23 2013We define the LS-category cat_g by means of covers of a space by general subsets, and show that this definition coincides with the classical Lusternik-Schnirelmann category for compact metric ANR spaces. We apply this result to give short dimension theoretic ... More
On the prime divisors of elements of a $D(-1)$ quadrupleSep 17 2013We show that if {1, b, c, d} is a D(-1) diophantine quadruple with b<c<d and c=1+s^2, then the cases s=p^k, s=2p^k, c=p and c=2p^k do not occur, where p is an odd prime and k is a positive integer. For the integer d=1+x^2, we show that it is not prime ... More
A complete classification of well-rounded real quadratic ideal latticesFeb 05 2019We provide a complete classification of well-rounded ideal lattices arising from real quadratic fields. We show that the ideals that give rise to such lattices are precisely the ones that correspond to divisors $a$ of the discriminant $d$ that satisfy ... More
Calibrating Black Box Classification Models through the Thresholding MethodMay 20 2017Jun 05 2017In high-dimensional classification settings, we wish to seek a balance between high power and ensuring control over a desired loss function. In many settings, the points most likely to be misclassified are those who lie near the decision boundary of the ... More
Motivic Decomposition of Projective Pseudo-homogeneous VarietiesSep 21 2015Nov 08 2015Let $G$ be a semi-simple algebraic group over a perfect field $k$. A lot of progress has been made recently in computing the Chow motives of projective $G$-homogenous varieties. When $k$ has positive characteristic, a broader class of $G$-homogeneous ... More
Review on Giant Magnetoelectric effects in Oxide ferromagnetic/ferroelectric Layered StructuresJan 29 2004The synthesis of layered ferrite-lead titanate zirconate (PZT) and lanthanum nanganite-PZT and the observation of giant magneto-electric interactions are discussed. The ferrites used in our studies included pure and Zn substituted cobalt-, nickel- and ... More
Adaptive Greedy Algorithms for Stochastic Set Cover ProblemsMar 20 2018Jun 15 2018We study adaptive greedy algorithms for the problems of stochastic set cover with perfect and imperfect coverages. In stochastic set cover with perfect coverage, we are given a set of items and a ground set B. Evaluating an item reveals its state which ... More
Logical analysis of the Bohr Complementarity Principle in Afshar's experiment under the NAFL interpretationApr 15 2005Jun 07 2010The NAFL (non-Aristotelian finitary logic) interpretation of quantum mechanics requires that no `physical' reality can be ascribed to the wave nature of the photon. The NAFL theory QM, formalizing quantum mechanics, treats the superposed state ($S$) of ... More
Good Reduction of Unitary Groups of Quaternionic Skew-Hermitian FormsJun 04 2019Given a field $K$ equipped with a set of discrete valuations $V$, we develop a general theory to relate ramification of skew-hermitian forms over a quaternion $K$-algebra $Q$ to ramification of quadratic forms over the function field $K(Q)$ obtained via ... More
Stability and dynamical properties of material flow systems on random networksFeb 12 2009The theory of complex networks and of disordered systems is used to study the stability and dynamical properties of a simple model of material flow networks defined on random graphs. In particular we address instabilities that are characteristic of flow ... More
Herding the Crowd: Automated Planning for Crowdsourced PlanningJul 29 2013There has been significant interest in crowdsourcing and human computation. One subclass of human computation applications are those directed at tasks that involve planning (e.g. travel planning) and scheduling (e.g. conference scheduling). Much of this ... More
Energetics of a rotating charged black hole in 5-dimensional supergravityFeb 18 2009Jan 08 2010We investigate the properties of the event horizon and static limit for a charged rotating black hole solution of minimal supergravity theory in (1 + 4) dimension. Unlike the four-dimensional case, there are in general two rotations, and they couple to ... More
Bonsai: Synthesis-Based Reasoning for Type SystemsAug 01 2017We describe algorithms for symbolic reasoning about executable models of type systems, supporting three queries intended for designers of type systems. First, we check for type soundness bugs and synthesize a counterexample program if such a bug is found. ... More
Robustness of the Drosophila segment polarity network to transient perturbationsJun 18 2009Continuous and Boolean models for the Drosophila segment polarity network have shown that the system is able to maintain the wild-type pattern when subjected to sustained changes in the interaction parameters and initial conditions. Embryo development ... More
Automorphic cohomology, motivic cohomology, and the adjoint $L$-functionSep 20 2016We propose a relationship between the cohomology of arithmetic groups, and the motivic cohomology of certain (Langlands-)attached motives. The motivic cohomology group in question is that related, by Beilinson's conjecture, to the adjoint $L$-function ... More
Phase Transitions in Operational RiskSep 14 2006Dec 06 2006In this paper we explore the functional correlation approach to operational risk. We consider networks with heterogeneous a-priori conditional and unconditional failure probability. In the limit of sparse connectivity, self-consistent expressions for ... More
Automated Detection of Serializability Violations under Weak ConsistencyJun 21 2018While a number of weak consistency mechanisms have been developed in recent years to improve performance and ensure availability in distributed, replicated systems, ensuring correctness of transactional applications running on top of such systems remains ... More
Periods of quaternionic Shimura varieties. IOct 01 2016We study "quadratic periods" on quaternionic Shimura varieties and formulate an integral refinement of Shimura's conjecture regarding Petersson inner products of automorphic forms that are related by the Jacquet-Langlands correspondence. The main result ... More
Automorphic cohomology, motivic cohomology, and the adjoint $L$-functionSep 20 2016Jan 12 2017We propose a relationship between the cohomology of arithmetic groups, and the motivic cohomology of certain (Langlands-)attached motives. The motivic cohomology group in question is that related, by Beilinson's conjecture, to the adjoint $L$-function ... More
Slot-mode-coupled optomechanical crystalsJul 20 2012We present a design methodology and analysis of a cavity optomechanical system in which a localized GHz frequency mechanical mode of a nanobeam resonator is evanescently coupled to a high quality factor (Q>10^6) optical mode of a separate nanobeam optical ... More
Imaging Nanophotonic Modes of Microresonators using a Focused Ion BeamDec 22 2015Optical microresonators have proven powerful in a wide range of applications, including cavity quantum electrodynamics, biosensing, microfludics, and cavity optomechanics. Their performance depends critically on the exact distribution of optical energy, ... More
Integration of fiber coupled high-Q silicon nitride microdisks with atom chipsMay 29 2006Sep 27 2006Micron scale silicon nitride (SiN_x) microdisk optical resonators are demonstrated with Q = 3.6 x 10^6 and an effective mode volume of 15 (\lambda / n)^3 at near visible wavelengths. A hydrofluoric acid wet etch provides sensitive tuning of the microdisk ... More
Ultrabroadband supercontinuum generation and frequency-comb stabilization using on-chip waveguides with both cubic and quadratic nonlinearitiesApr 12 2017Using aluminum-nitride photonic-chip waveguides, we generate optical-frequency-comb supercontinuum spanning from 500 nm to 4000 nm with a 0.8 nJ seed pulse, and show that the spectrum can be tailored by changing the waveguide geometry. Since aluminum ... More
Chip-integrated visible-telecom photon pair sources for quantum communicationMay 10 2018Photon pair sources are fundamental building blocks for quantum entanglement and quantum communication. Recent studies in silicon photonics have documented promising characteristics for photon pair sources within the telecommunications band, including ... More
Experimental demonstration of a high quality factor photonic crystal microcavityJun 16 2003Sub-threshold measurements of a photonic crystal (PC) microcavity laser operating at 1.3 microns show a linewidth of 0.10 nm, corresponding to a quality factor Q ~ 1.3x10^4. The PC microcavity mode is a donor-type mode in a graded square lattice of air ... More
Photonic-crystal-reflector nano-resonators for Kerr-frequency combsApr 15 2019We demonstrate Kerr-frequency-comb generation with nanofabricated Fabry-Perot resonators with photonic-crystal-reflector (PCR) end mirrors. The PCR group-velocity-dispersion (GVD) is engineered to counteract the strong normal GVD of a rectangular waveguide ... More
Two-photon interference using background-free quantum frequency conversion of single photons from a semiconductor quantum dotJul 17 2012We show that quantum frequency conversion (QFC) can overcome the spectral distinguishability common to inhomogeneously broadened solid-state quantum emitters. QFC is implemented by combining single photons from an InAs quantum dot (QD) at 980 nm with ... More
Improving the performance of bright quantum dot single photon sources using amplitude modulationAug 10 2012Single epitaxially-grown semiconductor quantum dots have great potential as single photon sources for photonic quantum technologies, though in practice devices often exhibit non-ideal behavior. Here, we demonstrate that amplitude modulation can improve ... More
Photonic-crystal-reflector nano-resonators for Kerr-frequency combsApr 15 2019Apr 17 2019We demonstrate Kerr-frequency-comb generation with nanofabricated Fabry-Perot resonators with photonic-crystal-reflector (PCR) end mirrors. The PCR group-velocity-dispersion (GVD) is engineered to counteract the strong normal GVD of a rectangular waveguide ... More
Optical loss and lasing characteristics of high-quality-factor AlGaAs microdisk resonators with embedded quantum dotsDec 11 2004Optical characterization of AlGaAs microdisk resonant cavities with a quantum dot active region is presented. Direct passive measurement of the optical loss within AlGaAs microdisk resonant structures embedded with InAs/InGaAs dots-in-a-well (DWELL) is ... More
Combined atomic force microscopy and photoluminescence imaging to select single InAs/GaAs quantum dots for quantum photonic devicesDec 06 2016We report on a combined photoluminescence imaging and atomic force microscopy study of single, isolated self-assembled InAs quantum dots (density <0.01 um^(-2) capped by a 95 nm GaAs layer, and emitting around 950 nm. By combining optical and scanning ... More
Multiple time scale blinking in InAs quantum dot single-photon sourcesJun 03 2013Apr 21 2014We use photon correlation measurements to study blinking in single, epitaxially-grown self-assembled InAs quantum dots situated in circular Bragg grating and microdisk cavities. The normalized second-order correlation function g(2)(\tau) is studied across ... More
Simultaneous Wavelength Translation and Amplitude Modulation of Single Photons from a Quantum DotMay 17 2011Aug 19 2011Hybrid quantum information devices that combine disparate physical systems interacting through photons offer the promise of combining low-loss telecommunications wavelength transmission with high fidelity visible wavelength storage and manipulation. The ... More
Black Hole Instabilities and Exponential GrowthJan 12 2015Aug 26 2015Recently, a general analysis has been given of the stability with respect to axisymmetric perturbations of stationary-axisymmetric black holes and black branes in vacuum general relativity in arbitrary dimensions. It was shown that positivity of canonical ... More
Structure, molecular dynamics, and stress in a linear polymer under dynamic strainDec 27 2010The structural properties of a linear polymer and its evolution in time have a strong bearing on its anisotropic stress response. The mean-square bond length and mean bond angle are the critical parameters that influence the time-varying stress developed ... More
Lexical State AnalyzerAug 14 2013Lexical states provide a powerful mechanism to scan regular expressions in a context sensitive manner. At the same time, lexical states also make it hard to reason about the correctness of the grammar. We first categorize the related correctness issues ... More
New Insights from an Analysis of Social Influence Networks under the Linear Threshold ModelFeb 06 2010We study the spread of influence in a social network based on the Linear Threshold model. We derive an analytical expression for evaluating the expected size of the eventual influenced set for a given initial set, using the probability of activation for ... More
Picard-Vessiot Extensions For Unipotent Algebraic GroupsFeb 15 2011Let F be a differential field of characteristic zero. In this article, we construct Picard-Vessiot extensions of F whose differential Galois group is isomorphic to the full unipotent subgroup of the upper triangular group defined over the field of constants ... More
Molecular gas associated with the IRAS-Vela shellJun 11 1999We present a survey of molecular gas in the J = 1 -> 0 transition of 12CO towards the IRAS Vela shell. The shell, previously identified from IRAS maps, is a ring-like structure seen in the region of the Gum Nebula. We confirm the presence of molecular ... More
On the existence of ethylenediaminetetraacetic acid (EDTA) doped zinc sulphate heptahydrate crystalJun 13 2015It is argued that the ethylenediaminetetraacetic acid (EDTA) doped zinc sulphate heptahydrate crystal reported by Raja et al Spectrochim Acta 99A (2012) 23 is the well known zinc sulphate heptahydrate.
A Comparative Study: Adaptive Fuzzy Inference Systems for Energy Prediction in Urban BuildingsSep 24 2018This investigation aims to study different adaptive fuzzy inference algorithms capable of real-time sequential learning and prediction of time-series data. A brief qualitative description of these algorithms namely meta-cognitive fuzzy inference system ... More
Formation Control in Multi-Agent Systems Over Packet Dropping LinksJun 27 2015One major challenge in implementation of formation control problems stems from the packet loss that occur in these shared communication channel. In the presence of packet loss the coordination information among agents is lost. Moreover, there is a move ... More